European Human Genetics Conference 2007 June 16 – 19, 2007 ...

Molecular and biochemical basis of disease
technique to define key molecules involved in Grm1 mediated synaptic
activity.
P0751. Molecular studies on chromosome 9p haploinsufficiency
and DMRT1 gene mutations in 46,XY patients with gonadal
dysgenesis
M. P. De Mello 1 , F. B. Coeli 1 , J. G. Assumpção 2 , T. M. Castro 1 , A. T. Maciel-
Guerra 3 , A. P. Marques-de-Faria 3 , M. T. M. Baptista 4 , G. Guerra-Jr 5 ;
1 Centro de Biologia Molecular e Engenharia Genética, Campinas, Brazil,
2 Centro Infantil Boldrini, Campinas, Brazil, 3 Departamento de Genética Médica,
Campinas, Brazil, 4 Departamento de Clínca Médica, Campinas, Brazil, 5 Centro
de Investigação em Pediatria, Campinas, Brazil.
SRY gene is responsible for testis determining in mammals. Among
patients with gonadal dysgenesis (GD), only 15-20% presents an inactivating
mutation in SRY coding region. It is well known that 9p chromosomal
deletion can cause sex reversal in 46,XY individuals. In the
present study, 9p haploinsufficiency was invstigated using five different
9p microsatellites: D9S1779, D9S1858, D9S143, D9S54, D9S1813.
Were included thirty-three SRY-normal non-related patients and seven
46,XY individuals of a family, three with GD (one complete and two
partial), the father and three normal siblings all of them bearing the
R30I SRY mutation. Homo- or hemizygosis for five and four loci was
observed in one and two patients, respectively. The three affected individuals
of the family bore identical 9p genotype, which was different
from normal individuals in the sibling. DMRT1 gene maps to 9p24.3
within the sex reversal region on 9p. The DMRT1 g.133T>A nucleotide
change was observed in 24 T/T homozygous and in 9 T/A heterozygous
patients. This results in S45T mutation but is considered a neutral
SNP (rs3739583). Interestingly, the A allele is the most frequent in
four out of five populations deposited in database, whereas this study
showed frequencies of 76% and 23% for T and A, respectively. The
g.52198T>C and g.52308C>T variations in exon 3 were detected in
one patient; both are rare SNPs. Finally, a new 3’UTR g.126313insT
was found in a heterozygous patient. The involvement of those SNPs
on either function or expression of DMRT1 must be investigated to
confirm them as causing DG.
P0752. Borate transporter SLC4A11 mutations cause both
Harboyan syndrome and non-syndromic corneal endothelial
dystrophy
J. Desir, G. Moya, O. Reish, N. Van Regemorter, H. Deconinck, K. L. David, F.
M. Meire, M. Abramowicz;
Medical Genetics Department, Hopital Erasme-ULB, Brussels, Belgium.
Harboyan syndrome (CDPD) consists of congenital corneal endothelial
dystrophy and progressive perceptive deafness and is transmitted
as an autosomal recessive trait. CDPD and autosomal recessive,
non-syndromic congenital hereditary endothelial corneal dystrophy
(CHED2) both map at overlapping loci at 20p13, and mutations of
SLC4A11 were recently reported in CHED2. We here report genotype
studies in six families with CDPD and one family with either CHED or
CDPD, from various ethnic backgrounds (in the seventh families hearing
loss could not be assessed because of the proband’s young age).
We found novel SLC4A11 mutations in all patients. Why some mutations
cause hearing loss in addition to corneal dystrophy is presently
unclear. Our findings extend the implication of the SLC4A11 borate
transporter beyond corneal dystrophy to perceptive deafness.
P0753. HAX-1 is a new interacting protein of phospholamban
and a novel regulator of calcium homeostasis and cardiac cell
survival
E. Vafiadaki 1 , D. Sanoudou 1 , D. A. Arvanitis 1 , D. H. Catino 2 , E. G. Kranias 3,1 , A.
Kontrogianni-Konstantopoulos 2 ;
1 Foundation for Biomedical Research, Athens, Greece, 2 Department of Physiology,
University of Maryland, Baltimore, MD, United States, 3 Department of
Pharmacology and Cell Biophysics, University of Cincinnati, Cincinnati, OH,
United States.
Phospholamban (PLN), a 52 amino acid transmembrane protein of
the sarcoplasmic reticulum (SR), is a key regulator of Ca 2+ -homeostasis
and contractility in the heart. Its regulatory effects are mediated
through its interaction with the sarcoplasmic reticulum Ca 2+ -ATPase,
(SERCA2a), resulting in alterations of its Ca 2+ -affinity. Impaired SR
Ca 2+ cycling is a characteristic of human heart failure and mutations
in PLN have been associated with dilated cardiomyopathy. To iden-
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tify additional proteins that may interact and thus regulate PLN, we
screened an adult human cardiac cDNA library using the yeast twohybrid
system.
We identified HS-1 associated protein X-1 (HAX-1), a ubiquitously expressed
mitochondrial protein with anti-apoptotic function, as a new
PLN-binding partner. The minimal binding regions were mapped to
amino acids 203-245 for HAX-1 and 16-22 for PLN. GST pull-down
and in vitro binding assays confirmed the direct interaction between
PLN and HAX-1, while kinetic studies determined a K D of ~1μM as the
binding affinity of the protein complex. The interaction was found to be
modulated by PLN phosphorylation and changes in Ca 2+ concentration.
Moreover, SERCA2a was also detected in the pull down samples,
suggesting that HAX-1 forms part of the PLN/SERCA2a complex. Immunofluorescence
studies localized HAX-1 to the mitochondria. However,
in the presence of PLN, HAX-1 redistributed and co-localized at
the endoplasmic reticulum. Importantly, the anti-apoptotic function of
HAX-1 was found to be enhanced in the presence of PLN, indicating
an important role of the PLN/HAX-1 interaction in cell survival, possibly
through the regulation of SR Ca 2+ -homeostasis and consequent
mitochondrial Ca 2+ redistribution.
P0754. Mutation analysis of the GJB2 gene in Latvian patients
with nonsyndromic sensorineural hearing loss
O. Sterna 1 , N. Pronina 1 , I. Grinfelde 1 , S. Kuske 2 , A. Krumina 3 , R. Lugovska 1 ;
1 Medical Genetics clinics, Latvian State Childrens` Hospital, Riga, Latvia, 2 2Latvian
Childrens` Hearing centre, Riga, Latvia, 3 Riga Stradins University, Riga,
Latvia.
Mutations in the GJB2 gene at the DFNB1 locus on chromosome
13q11-q12 have been established to be the major cause of nonsyndromic
sensorineural hearing impairment (NSHI) in different populations.
Up to date there are reported 110 different GJB2 mutations.One
particular frame shift mutation named 35delG is the most prevalent in
the populations of the Caucasian origin.
The aim of our work was to investigate the prevalence of the GJB2
gene mutations within Latvian NSHI individuals from 41 families. All
samples were screened for 35delG mutation using RFLP method. Remaining
GJB2 mutations were identified by the direct sequencing.
Four different mutations in the GJB2 gene have been identified in Latvian
patients with nonsyndromic sensorineural hearing loss: 35delG,
311-324del14, 235delC and M34T.
The most prevalent mutation in patients with NSHI in Latvia is 35delG
(62% of all probands are homozygotes for this mutation). Frequency of
311-324del14 mutation is 7%, but 235delC and M34T mutations were
found in 2% of patients.
P0755. Integrated approach to the study of Congenital Heart
Diseases
A. Baban 1 , M. Marini 1 , G. Trocchio 2 , M. Lerone 1 , M. Di Duca 3 , G. Gimelli 1 , M.
Pelegrini 4 , G. Pongigliono 4 , R. Ravazzolo 1 ;
1 Molecular Genetics and Cytogenetics Unit,, Genoa, Italy, 2 Cardiology Unit,
Genoa, Italy, 3 Laboratory of Nephrology, G. Gaslini Institute, Genova, Genoa,
Italy, 4 Cardiology Unit, G. Gaslini Institute, Genoa, Italy.
This study is part of a research project financed by the European Community
(Health-e-Child, Contract n°: IST-2004-027749), that involves
three Pediatric European Centers. It foresees vertical integration of
epidemiological, clinical, radiological, laboratory, biological, and genetic
data.
The study includes congenital heart diseases that lead to Right Ventricular
Overload (RVO): Atrial Septal Defects (ASD), Post-operative
Tetralogy of Fallot (ToF) and Anomalous Pulmonary Venous Return
(APVR). The study aims to collecting the following data :
-Clinical Evaluation: demographic information, personal and family history,
family pedigree, and detailed physical examination.
-Instrumental Evaluation: Electrocardiogram (ECG), Holter ECG, Signal-Averaged
ECG, Chest X-ray, 2D and 3D echocardiography, tissue
doppler imaging, acoustic boundary detection, integrated backscatter,
color kinesis, transesophageal echocardiography and magnetic resonance
imaging, cardiac catheterisation.
-Chromosomal analysis by standard karyotyping;
-In case of normal karyotype, screening of three candidate genes
(GATA4, TBX5 e NKX2.5), known to be fundamental for normal cardiac
development and function.
-The negativity of the previously mentioned tests make the patient can-